A weather radar system measures rainfall intensity within a scanned area. Intense rainfall may include severe turbulence which can be hazardous to aircraft flight. The weather radar system includes an antenna receiver/transmitter unit. The unit emits a concentrated beam of microwave energy. The returned echo indicates the intensity of detected targets. The detected intensity is displayed as color coded targets depicting echos on a display. The intensity of the rainfall at a given location is indicated by the color displayed. For example, black represents very light or no precipitation, green represents light precipitation, yellow represents moderate precipitation, red represents heavy precipitation and magenta represents very heavy precipitation.
A radar beam increases in width with increased distance from the sensor. At a large distance the beam is very wide, sometimes on the order of tens of miles. The radar sensor detects a target at a particular distance based on the average intensity of the echo across the full beam width. FIG. 1 illustrates a radar beam 100 transmitted from an airborne weather radar 102. As shown, the width (w) of the beam 100 increases with distance (d) from the airborne radar 102.
A typical thunderstorm is only one mile in diameter. Thus, a storm detected within a beam that is 10 miles wide may only return an echo indicating one-tenth the intensity because of intensity averaging over the full beam width. Thus, the intensity is incorrectly represented as green instead of showing regions of red. The returned echo is misleading because it does not depict the real intensity of the weather ahead.
A weather radar display system displays a beam indicator indicative of a radar beam. A beam dimension routine in the weather radar display system computes dimensions of the beam indicator. A display in the weather radar display system shows a weather target found by a radar signal of the radar beam. The beam indicator sweeps over the displayed weather target. The width of the beam indicator is relative to the width of the weather target providing an indication of the reliability of the displayed weather target.
The displayed beam indicator is opaque and provides an indication that the radar signal is being transmitted and received. The beam dimension routine computes the dimensions of the beam indicator to be displayed dependent on the beam width of an airborne radar antenna which transmits and receives the radar signal.
The angle of the beam indicator to be displayed decreases as the diameter of the antenna is increased. The beam indicator follows the center of an airborne radar sweep. The width of the beam indicator is dependent on distance from the source of the radar signal. The dimensions of the beam indicator remain constant as the scale of the display is modified. The beam indicator is wedge-shaped.